This invention relates to new and useful improvements in tracheal tube assemblies, and particular the inflation assembly thereof.
A tracheal tube is a medical device commonly used in intensive care and during operations under general anaesthesia. It consists of a flexible tube with the distal end surrounded by a cuff. When inserted into the trachea inflation of this cuff seals the tube to the tracheal wall, facilitates ventilation and also secures the patient's airway from aspiration of gastric contents and any other foreign material.
Conventionally, air or other fluid is injected into the tracheal cuff by means of an inflation syringe attached to the pilot balloon. This system has many inherent disadvantages. Manual inflation by syringe is inconvenient, might require the assistance of a second party and delays the inflation of the cuff. It is especially important to protect the patient's airway when the risk of aspiration of gastric contents is high as in anaethesia for Caesarean section, the traumatized patient and operations for acute abdominal conditions. It is in these situations a system is especially indicated which provides rapid and non-manual inflation of the tracheal cuff, eliminating time delay and need for assistance during intubation of the trachea. Over-compression of the tracheal mucosa by the inflated cuff is another problem with the conventional tracheal tube inflation assembly. The pressure is the tracheal cuff can only be estimated crudely by palpation of the pilot balloon. With manual inflation, the tracheal cuff pressure may frequently exceed the desired pressure (approx. 20 mmHg.). Also during general anaesthesia with nitrous oxide, diffusion of nitrous oxide into the tracheal cuff will increase the pressure exerted on the tracheal wall. This results in a high incidence of complications (sore throat, hoarseness and tracheal damage) after removal of the tube. To prevent the foregoing the cuff pressure should be checked and adjusted frequently. This is inconvenient and time consuming and seldom done in practice.
Many attempts have been made in order to endeavour to correct these problems and prior art known to applicants includes the following:
Canadian Pat. No. 1,052,215 (Bazzell et al). This shows a catheter with an inflation indicator for the cuff or cuff balloon. The inflation measuring device includes a collar substantially encompassing the signal member or balloon.
U.S. Pat. No. 4,020,849 (Jackson) discloses a cuff inflation arrangement for tracheal tubes including a connector member incorporating an auxiliary passage having an entrance device for inflating the cuff with breathing air. The cuff is automatically inflated and the filling process terminated at a desire level for retaining sealing pressure in the cuff.
U.S. Pat. No. 4,116,201 (Shah) discloses a catheter with an inflation control valve for controlling the filling of an inflatable balloon through an inflation lumen.
U.S. Pat. No. 4,134,407 (Elan) shows an external pressure-volume monitor for an endotracheal cuff which provides automatic indication of the pressure in the cuff.
U.S. Pat. No. 3,848,605 (Harautuneia et al) discloses an endotracheal tube including a pilo balloon which serves as a low pressure reservoir.
U.S. Pat. No. 3,794,043 (McGinnis) features an endotracheal tube with an inflatable cuff and an associated check valve for controlling the admitting and release of air to an inflatable balloon.
U.S. Pat. No. 3,642,005 (McGinnis) discloses an endotracheal tube including an inflatable cuff which provides for automatic regulation of the air pressure.
U.S. Pat. No. 4,248,222 (Jaeger et al) discloses an endotracheal tube including a relief valve.
Journal of Thoracic and Cardiovascular Surgery 1972, pages 747-756 Magovern et all shows an occluding cuff system with a high-residual volume cuff inflated by a pressure regulating mechanism which utilizes a specially designed external balloon and a pressure regulating valve.
None of the known prior art cited above teaches a completely satisfactory solution and does not address the principal problems involved, namely, rapid self-inflation and constant pressure control.